Need this to be solved as soon as possible A 6-foot-long circular pipe used to t

Question

Need this to be solved as soon as possible

A 6-foot-long circular pipe used to transfer hot water has inner and outer diameters of 1 inch 1.25 inches, respectively. The pipe is made of copper. The copper alloy is unknown. Inside the pipe, hot water (170 degreeF) flows very quickly (average velocity is 20 ft/sec.) The convective heat transfer coefficient between the flowing water and the inside of the pipe is unknown. The properties for water at this temperature are: Thermal Conductivity = 0.385 Btu/hr-ft-degreeF Specific Heat = 1.001 Btu/Ibm-degreeF Density = 61 Ibm/ft3 The environment outside the pipe is 73 degreeF air and the convective heat transfer coefficient is 2.2 Btu/hr-ft2-degreeF. Estimate the rate of heat transfer from the flowing water and the air. Estimate the temperature change of the water as it moves through the 6-feet length of pipe. Hint: The mass flowrate of the water is: where is the average velocity of the pipe.

Explanation / Answer

q=DeltaT/R

Rconv.in = 1/hinAin = 1/(700btu/hr ft^2 F)(1/12ft)(pi)(6ft) = 9.09*10^-4 hr F/Btu

Rcond = ln(Dout/Din)/(2piKL)= ln(1.25/1)/2pi(0.385Btu/hrftF)(6ft) = 0.01537 hr F/Btu

Rconv.out = 1/houtAhout = 1/(2.2Btu/hrft^2F)(pi)(1.25/12ft)(6ft) = 0.2315 hr F/Btu

Rtotal= 0.0137 = 9.09*10^-4+0.2315 = 0.247779 hr F/Btu

q = deltaT/R = (170-73) F /(0.247779 hr F/Btu)

q= 391.47 Btu/hr.

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